RET/PTC oncogene expression in papillary thyroid carcinoma and its correlation with clinicopathologic findings

Abstract

Papillary thyroid carcinomas (PTCs) are the most frequent type of malignant thyroid tumors. Somatic rearrangements of the ret protooncogene are frequent genetic events in PTCs. Studies that are designed to determine the correlation between ret/PTC expression and biological characteristics, pathologic features, clinical behavior of PTC gave different results. We investigated the expression of ret/PTC oncogene product by immunohistochemistry to determine the relationship of ret/PTC expression with initial histopathologic findings, clinical markers, and prognosis in 44 papillary thyroid cancer patients. A monoclonal antibody was used. Patients between years 1995 and 2003 with a mean follow-up of 59 +/- 25 months (range 24-120) were evaluated retrospectively. Study group consisted of 38 women and 6 men, with a mean age of 44.6 +/- 11.2 years. Positive immunostaining was recorded if more than 5% of the tumor cells had intracytoplasmic staining. Adjacent nontumoral thyroid tissue was used as control. Seventeen (39%) of 44 patients showed intracytoplasmic staining specific for ret/PTC. Lymph node metastasis, capsule invasion, vascular invasion, soft tissue invasion, and multicentricity rates at initial examination were not significantly different between ret/PTC positive and negative patients. Turner size, follow-up period, age, and gender were not significantly different between ret/PTC positive and negative patients, either. These findings suggest that ret/PTC expression has no prognostic value in papillary thyroid cancer.